Periodontal disease or gum disease as it is often called can be defined as an infection and inflammation of the gingiva or gums and loss of underlying alveolar bone support. There are varying levels of severity of the disease. The mildest cases are clinically termed gingivitis (inflamed and bleeding gums). More severe cases are clinically known as periodontitis and can involve loss of bone support. Gingivitis is reversible and can often be eliminated with a thorough dental prophylaxis followed by improved personal oral hygiene procedures. If gingivitis is not controlled, the disease often progresses into periodontitis.
Periodontitis is not only characterized by bacterial infection and inflammation, it is also accompanied by the formation of periodontal pockets (spaces between the teeth and gums) and bone deterioration which can lead to tooth loss. Periodontitis is recurring, progressive, and episodic. There is no cure at this time. Effective treatment is to apply professional intervention to halt disease progression.
Professional intervention may involve surgical or nonsurgical procedures. Nonsurgical treatment consists of periodic professional scaling, root planing, and soft tissue curettage, in combination with conscientious home care by brushing and flossing on the part of the patient. Surgical treatment involves gingivectomy and flap surgery to recontour the soft and hard tissue around the diseased areas.
In recent years, it has become increasingly recognized that control of periodontitis may be possible with the use of antimicrobial agents delivered to the infected site. Systemic antibiotics taken orally or intramuscularly have been successfully used, but due to the concern about allergic responses, the development of resistance, and the treatment of the whole person rather than the specific infection site, their use is recommended only in the severest of periodontal cases.
Treatment by mouth rinse and other topically applied oral medicinal agents does not allow the antibacterial agents to penetrate into the periodontal pocket where they are needed. Irrigation of the pockets with these agents has shown some effects on gingivitis, but the short time of exposure with irrigation solutions and the rapid removal of any therapeutic agent by the outward flow of the crevicular fluid make this type of treatment ineffective with severe cases of periodontitis.
The most recent proposed methods of treating periodontitis with the local delivery of chemotherapeutic agents have involved the placement of these agents directly into the periodontal pocket. These include the cellulose hollow fibers loaded with tetracycline described in U.S. Pat. No. 4,175,326 to Goodson, the ethylcellulose films loaded with metronidazole described in U.S. Pat. No. 4,568,535 to Loesche, the absorbable putty-like material described in U.S. Pat. No. 4,568,536 to Kronenthal, the ethylene vinyl acetate fibers loaded with tetracycline described in the European patent application No. 84401985.1 to Goodson, and the biodegradable microspheres and matrix described in U.S. Pat. No. 4,685,883 to Jernberg. All of these delivery systems involve placing the product directly into the periodontal pocket.
Although the space between the gingival tissue and the tooth in periodontal disease is called a pocket, it is really only a potential space in which bacteria can grow. The insertion of a delivery system within this potential space is more difficult than the simple placement of a material within a well-defined pocket. Moreover, the shape of the pocket or potential space is not regular, but often contoured based upon the shape of the tooth and the extent of the disease. Thus, placement of a film or fiber within the pocket requires careful fitting to fill the pocket but not extend beyond the gingival margin. Any material extending outside the pocket will be removed by normal oral hygiene procedures unless the material is either adhered to the tissue or tooth or covered by a periodontal dressing.
In addition to the retention problems associated with normal dental care, the outward flow of crevicular fluid and the mechanical action of the teeth and the gums during eating cause most materials placed within the periodontal pocket to be expelled in a relatively short time. It is well known that carbon particles placed within a periodontal pocket are all displaced within a few hours. Because of these retention problems, most periodontal delivery systems for chemotherapeutic agents are either adhesively bound to the tooth or the tissue within the pocket. However, adhesion to a wet surface such as that within the pocket is extremely difficult and normally the adhesion deteriorates rapidly. Thus, retention within the pocket is short-lived.
The other solution to retention of a delivery system within the pocket is to use a periodontal dressing to cover the pocket. Periodontal dressings are also adhesives and their adhesion to wet surfaces such as a tooth or gum tissue is difficult; and most periodontal dressings do not adhere long within the mouth. In addition, they are uncomfortable to the wearer and they tend to collect food particles and bacteria.
Because of these problems with proper placement of a local delivery system within the periodontal pocket and the retention of the system for sufficient time to kill all of the periodontal pathogens, there is a need for a better delivery system to deliver chemotherapeutic agents to the site of infection. Moreover, recent research indicates that the bacteria often responsible for periodontal disease exist not only in the periodontal pocket but also within the gingival tissue. This is especially true for localized juvenile periodontitis. The only way to treat this form of periodontal disease has been to administer systemic antibiotics which can attack the bacterial infection within the gingival tissue itself. Several researchers have recently shown that the bacteria responsible for periodontal disease have also been found in the tissue of patients with normal adult periodontitis.
Thus, delivery systems containing chemotherapeutic agents when placed within the periodontal pocket will kill the bacteria there, but these agents will not penetrate the gingival tissue to destroy the bacteria located intragingivally. These bacteria subsequently repopulate the periodontal pocket after the chemotherapeutic agent has been totally released or exhausted. There is therefore a need for a local delivery system that will destroy not only the periodontal pathogens within the periodontal pocket but also within the gingival tissues.